Helical ground anchor and method of its use

ABSTRACT

A ground anchor system for anchoring a post comprises a base plate, a housing extending above the base plate, an anchor extending below the base plate, the anchor comprising a tapered helix having a thread encircling a tube which tapers inwardly towards the lower end of the anchor, and a boring tip at the lower end of the anchor. The tapered helical thread of the anchor firmly engages with the ground into which it is threaded to provide a solid support to a post inserted in the housing. Helix taper and length, and thread taper and pitch may be selected to optimize retention and lateral support of a post in a particular ground type.

TECHNICAL FIELD OF THE INVENTION

The present invention relates generally to ground anchors. In particular, the invention relates to a ground anchor for securing and installing posts for use in fencing or other construction.

BACKGROUND OF THE INVENTION

Several problems arise when securing posts for construction, such as are used for fences, greenhouses, sheds, etc. in loose, wet, inaccessible or otherwise difficult ground. Firstly, the retention of a post in the ground is lessened by variable soil conditions such as soil compactness, water saturation, and variable water levels which may reduce the amount of force required to dislodge a post. Secondly, traditional wooden posts remaining in wet soils have a limited life span, usually no more than ten years, as they are susceptible to rot and decay when immersed in a moist soil environment. Thirdly, installed posts, whether pounded or reinforced by a concrete pour, are difficult to maintain, extract or adapt, and are generally non-reusable.

These problems may be overcome through use of a tapered helical anchor of durable material such as plastic or corrosion resistant metal, and a serviceable platform for the maintenance of the above ground portion of the supporting post structure. Temporary and seasonal fencing is possible using this durable and reusable design.

There are a number of desirable objectives in relation to screw-type ground anchors. Such anchors should preferably be made of plastic or other corrosion resistant material, and should be easy to install, maintain, extract and reuse. For ease of manufacture, they should be of an integrated design, and preferably hollow to reduce material costs. For optimal ground entry and post support, they should ideally provide a notched boring tip, and a continuous helix which tapers inward toward the base of the anchor and provides a wide, pitched thread. The anchor should also provide a secure post mount which is adaptable to a variety of posts. Existing ground anchors achieve some of these objectives, but with varying degrees of success.

It is known to provide a screw-type device for anchoring a post. Such a device is described in European Patent Patent No. 0542692 to Moore. Moore teaches a helical anchor pile preferably made of plastic and having a base plate for anchoring of a post to the top surface of the anchor. The anchor in Moore is directed to anchoring an otherwise free-standing structure such as a transmission tower.

It is also known to provide a screw-type ground anchor for low stress, temporary installations such as beach umbrellas. Such a device is described in U.S. Pat. No. 5,046,699 to Perreault. The anchor in Perreault provides a helix only at the lowermost end of the anchor. Such a helix is sufficient for temporary installations designed for easy removal, but would be insufficient for long term post installations.

Other helical ground anchors are known. In French Patent No. 2,571,771, Rovera discloses a screw-type ground anchor in which the anchoring helix does not taper until the lowermost region of the anchor, and the thread pitch is constant. Pylant, in U.S. Pat. No. 6,412,235, teaches a ground anchor with non-tapered screw threads only near the tip of the anchor.

SUMMARY OF THE INVENTION

In one embodiment, the invention comprises a ground anchor system for anchoring a post comprising a base plate, a housing extending above the base plate, an anchor extending below the base plate, the anchor comprising a tapered helix having a thread encircling a tube which tapers inwardly towards the lower end of the anchor, and a boring tip at the lower end of the anchor.

The base plate, housing, anchor and boring tip may be structurally integrated, and may be manufactured by injection over-molding onto a metal tube, by extrusion, or by casting.

The upper end of the helix may begin at the base plate or below the base plate a distance of no greater than 25% of the combined length of the anchor and boring tip. The lower end of the helix may end above the end of the boring tip a distance of no greater than 50% of the combined length of the anchor and boring tip.

The helix may taper inwardly towards the lower end of the anchor at a constant angle of between 1 and 30 degrees relative to the vertical plane, or at a continuously increasing angle in the range between 1 and 30 degrees relative to the vertical plane.

The angular pitch of the thread may be constant and may be between 3 and 30 degrees relative to the horizontal plane, or the thread mat taper from a first width proximal to the tube to a second narrower width distal to the tube.

The housing may comprise solid walls or non-solid walls. At least one interior wall of the housing may comprise friction enhancing means. The friction enhancing means may be at least one vertical ridge or a plurality of fins. The housing may further comprise post attachment means. The post attachment means may be one or more bolts, one or more screws, or a threaded adaptor lining the housing for receiving a threaded post. The housing further may comprise one or more insertable elements to reduce the horizontal cross-sectional area of the housing.

The boring tip may be crimped, and there may be an opening between the housing and the tube of the anchor. The material used to manufacture the base plate, housing, anchor and boring tip may be a plastic. The plastic may be a recycled polyethylene terephthalate, and it may be a dark colour.

In another embodiment, the invention comprises a ground anchor system for anchoring a post comprising a base plate, a housing extending above the base plate, an anchor extending below the base plate, the anchor comprising a tapered helix having a thread encircling a tube which tapers inwardly towards the lower end of the anchor, and a boring tip at the lower end of the anchor, wherein the helix begins at the base plate and ends above the end of the boring tip a distance of no more than 50% of the combined length of the anchor and boring tip and tapers inwardly towards the lower end of the anchor at an angle of between 1 and 30 degrees relative to the vertical plane, the thread has a constant angular pitch of between 3 and 30 degrees relative to the horizontal plane and tapers from a first width proximal to the tube to a second narrower width distal to the tube, and the base plate, housing, anchor and boring tip are manufactured by injection over-molding onto a metal tube.

In yet another embodiment the invention comprises a ground anchor system for anchoring a post comprising a base plate, a housing extending above the base plate, an anchor extending below the base plate, the anchor comprising a tapered helix having a thread encircling a tube which tapers inwardly towards the lower end of the anchor, and a boring tip at the lower end of the anchor, wherein the helix begins at the base plate and ends above the end of the boring tip a distance of no more than 50% of the combined length of the anchor and boring tip and tapers inwardly towards the lower end of the anchor at an angle of between 1 and 30 degrees relative to the vertical plane, the thread has a constant angular pitch of between 3 and 30 degrees relative to the horizontal plane and tapers from a first width proximal to the tube to a second narrower width distal to the tube, and the base plate, housing, anchor and boring tip are manufactured by extrusion.

In still another embodiment, the invention comprises a ground anchor system for anchoring a post comprising a base plate, a housing extending above the base plate, an anchor extending below the base plate, the anchor comprising a tapered helix having a thread encircling a tube which tapers inwardly towards the lower end of the anchor, and a boring tip at the lower end of the anchor wherein the helix begins at the base plate and ends above the end of the boring tip a distance of no more than 50% of the combined length of the anchor and boring tip and tapers inwardly towards the lower end of the anchor at an angle of between 1 and 30 degrees relative to the vertical plane, the thread has a constant angular pitch of between 3 and 30 degrees relative to the horizontal plane and tapers from a first width proximal to the tube to a second narrower width distal to the tube, and the base plate, housing, anchor and boring tip are manufactured by casting.

In yet another embodiment, the invention comprises a post anchoring system comprising a base plate, a housing extending above the base plate, an anchor extending below the base plate, the anchor comprising a tapered helix encircling a tube which tapers inward at its lower end, a boring tip at the lower end of the anchor, and a post inserted into the housing, wherein the length of the anchor is at least 25% of the length of the overall post anchoring system.

In still a further embodiment, the invention comprises a method of inserting a post anchor comprising the steps of vertically positioning the post anchor in a selected location with the tip of the post anchor in contact with the ground surface, driving the post anchor by driving means into the ground to a position in which the thread of the helix of the post anchor is in contact with the ground surface, placing a lever arm in the housing of the post anchor, simultaneously applying sufficient downward pressure and rotational torque to the lever arm to rotate the post anchor into the ground to a position in which the base plate is in contact with the ground surface, removing the lever arm, and positioning and affixing a post into the housing of the post anchor.

The driving means may comprise a drive shaft integrated with the lever arm.

Other aspects of the invention will be appreciated by reference to the description of the preferred embodiment which follows and to the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described by reference to the preferred embodiment and the drawings thereof in which:

FIG. 1 is a perspective view of the ground anchor, according to the invention;

FIG. 2 is a plan view of the ground anchor, according to the invention;

FIG. 3 is a cross-sectional view through line 3-3 of FIG. 2; and

FIG. 4 is a perspective view of an installation, according to the invention.

DETAILED DESCRIPTION OF BEST MODE AND PREFERRED EMBODIMENT OF THE INVENTION

As shown if FIGS. 1, 2 and 3, an integrated ground anchor and post mount housing device 2 comprises a housing 4 adjacent a base plate 6, the base plate adjacent an anchor segment. The anchor segment is a hollow tube 8 incorporating a helix 10 extending along a portion of its length, and a boring tip 12 at its lowermost end. The housing provides support for a post or other upright inserted therein. The base plate 6 connects the housing 4 to the anchor segment and defines the extent of insertion of the anchor into the ground. The anchor segment helix 10 has a wide and tapered thread 14 extending most of its length. The boring tip 12 is narrowed, crimped or cut to assist in the loosing of the soil for anchor segment insertion.

The length of the anchor segment preferably is at least 25% of the above ground height of the supported post. The hollow tube 8 may taper inwardly from the base plate towards the boring tip 12. Referring now to FIG. 2, the helical portion preferably begins at a distance a above the bottom end of the anchor of between 10% and 25% of the total length of the embedded portion of the anchor. The helix is continuous and has a taper b which may be fixed or may vary between 1 and 20 degrees relative to the vertical plane, increasing in angle from the terminus to the base plate. The helix preferably terminates at a distance c below the base plate. The angular pitch d of the thread 14 is preferably a constant angle of between 3 and 30 degrees relative to the horizontal plane. As in a conventional screw, the thread preferably is tapered, having a thicker width proximal to the central vertical axis of the ground anchor and narrowing distal to the vertical axis.

The tapered helical thread of the anchor firmly engages with the ground into which it is threaded to provide a solid support to a post inserted in the housing. Helix taper and length, and thread taper and pitch may be selected to optimize retention and lateral support of a post in a particular ground type.

The base plate preferably is of a design and dimensions sufficient for ensuring the lateral stability of the anchoring system and of sufficient strength to support the housing and anchor segments. The housing preferably provides support to the post and surrounds the lower end of the post on all sides for a distance of at least 10% of the overall length of the post. The housing may have solid walls 18, as shown in FIG. 1, or non-solid walls. For example, as shown in FIG. 2, the non-solid walls 20 may have a plurality of openings to reduce material requirements. One or more inserts 22 may be used for the accommodation of posts having a diameter smaller diameter posts. The inserts may be placed between the post and the housing walls to ensure a close fit.

Post support in the housing may be enhanced by one or more of the following mechanisms:

-   -   1. bolts or screws may be used to secure the post within the         housing;     -   2. a threaded adaptor may be disposed on the base plate to         permit the post to be screwed onto the base plate following         anchor installation;     -   3. a plurality of fins may be integrated into the interior         surface of the housing;     -   4. the post may be selected or machined to fit snugly in the         housing to enhance friction between the surfaces of contact of         the post and the housing;     -   5. inserts may be fitted into the housing to permit the securing         of smaller posts.

In one embodiment, the post may be molded or extruded integrally with the anchor to create a monolithic post and anchor structure.

To permit egress of water which may collect in the housing, an opening 24 may be provided through the base plate 6 between the housing 4 and the hollow tube 8 of the anchor segment to allow for drainage of water. This opening will also permit the escape of air displaced by insertion of the post into the housing.

Preferably, the ground anchor device is manufactured by extrusion, direct-injection molding or over-molding from plastic or corrosion-resistant metals such as aluminum. The hollow post design facilitates entry into the soil, adds to stability of the anchor in the ground, allows for drainage of water and equalisation of air pressure, and reduces material costs.

The helix of the ground anchor permits the post to be reused, and provides for increased lateral stability and retention, particularly in loose soils. The presence of a wide thread on the helix provides greater stability to the anchor by increasing the surface area which is contact with the soil. The boring tip loosens soil to facilitate entry of the helical thread into the ground.

An adaptable housing allows for different types of posts to be used in conjunction with the ground anchor, and facilitates maintenance and adaptation of the above-ground portion of the post as necessary. The base plate provides strength to the physical connection between the housing and the helical anchor and increases the lateral stability of the anchor in the ground.

According to one embodiment of the method of the invention, a post may be anchored into the ground according to the following steps:

-   -   1. the boring tip of the anchor segment is driven or pushed into         the ground until the edge of the first thread of the helix makes         contact with the ground;     -   2. a lever arm or drive shaft is placed into the housing;     -   3. downward pressure and torque are applied to the lever arm or         drive shaft to screw the anchor segment into the ground until         the base plate makes contact with the ground;     -   4. the lever arm or drive shaft is removed from the housing; and     -   5. a post is placed into the housing and affixed therein.

As shown in FIG. 4, a plurality of ground anchor and post mount housing devices 2 may be screwed into the ground surface until the base plates 6 are at the surface of the ground. A post 26 may be inserted into the housing 4 of each anchor. In one embodiment, anchored posts may be joined by rails to form a fence which is easily removable and reusable.

It will be appreciated by those skilled in the art that other variations of the preferred embodiment may also be practised without departing from the scope of the invention. 

1. A ground anchor system for anchoring a post comprising: a base plate, a housing extending above the base plate, an anchor extending below the base plate, the anchor comprising a tapered helix having a thread encircling a tube which tapers inwardly towards the lower end of the anchor, and a boring tip at the lower end of the anchor.
 2. The ground anchor system of claim 1 wherein the base plate, housing, anchor and boring tip are structurally integrated.
 3. The ground anchor system of claim 1 wherein the base plate, housing, anchor and boring tip are manufactured by injection over-molding onto a metal tube.
 4. The ground anchor system of claim 1 wherein the base plate, housing, anchor and boring tip are manufactured by extrusion.
 5. The ground anchor system of claim 1 wherein the base plate, housing, anchor and boring tip are manufactured by casting.
 6. The ground anchor system of claim 1 wherein the upper end of the helix begins at the base plate.
 7. The ground anchor system of claim 1 wherein the helix begins below the base plate a distance of no greater than 25% of the combined length of the anchor and boring tip.
 8. The ground anchor system of claim 1 wherein the lower end of the helix ends above the end of the boring tip a distance of no greater than 50% of the combined length of the anchor and boring tip.
 9. The ground anchor system of claim 1 wherein the helix tapers inwardly towards the lower end of the anchor at a constant angle of between 1 and 30 degrees relative to the vertical plane.
 10. The ground anchor system of claim 1 wherein the helix tapers inwardly towards the lower end of the anchor at a continuously increasing angle in the range between 1 and 30 degrees relative to the vertical plane.
 11. The ground anchor system of claim 1 wherein the angular pitch of the thread is constant and is between 3 and 30 degrees relative to the horizontal plane.
 12. The ground anchor system of claim 1 wherein the thread tapers from a first width proximal to the tube to a second narrower width distal to the tube.
 13. The ground anchor system of claim 1 wherein the housing comprises solid walls.
 14. The ground anchor system of claim 1 wherein the housing comprises non-solid walls.
 15. The ground anchor system of claim 1 wherein at least one interior wall of the housing comprises friction enhancing means.
 16. The ground anchor system of claim 1 wherein the friction enhancing means comprises at least one vertical ridge.
 17. The ground anchor system of claim 1 wherein the friction enhancing means comprises a plurality of fins.
 18. The ground anchor system of claim 1 wherein the housing further comprises post attachment means.
 19. The ground anchor system of claim 18 wherein the post attachment means comprises one or more bolts.
 20. The ground anchor system of claim 18 wherein the post attachment means comprises one or more screws.
 21. The ground anchor system of claim 18 wherein the post attachment means comprises a threaded adaptor lining the housing for receiving a threaded post.
 22. The ground anchor system of claim 1 wherein the housing further comprises one or more insertable elements to reduce the horizontal cross-sectional area of the housing.
 23. The ground anchor system of claim 1 wherein the boring tip is crimped.
 24. The ground anchor system of claim 1 further comprising an opening between the housing and the tube of the anchor.
 25. The ground anchor system of claim 1 wherein the material used to manufacture the base plate, housing, anchor and boring tip is a plastic.
 26. The ground anchor system of claim 25 wherein the plastic is a recycled polyethylene terephthalate.
 27. The ground anchor system of claim 25 wherein the plastic is a dark colour.
 28. A ground anchor system for anchoring a post comprising: a base plate, a housing extending above the base plate, an anchor extending below the base plate, the anchor comprising a tapered helix having a thread encircling a tube which tapers inwardly towards the lower end of the anchor, and a boring tip at the lower end of the anchor wherein the helix begins at the base plate and ends above the end of the boring tip a distance of no more than 50% of the combined length of the anchor and boring tip and tapers inwardly towards the lower end of the anchor at an angle of between 1 and 30 degrees relative to the vertical plane, the thread has a constant angular pitch of between 3 and 30 degrees relative to the horizontal plane and tapers from a first width proximal to the tube to a second narrower width distal to the tube, and the base plate, housing, anchor and boring tip are manufactured by injection over-molding onto a metal tube.
 29. A ground anchor system for anchoring a post comprising: a base plate, a housing extending above the base plate, an anchor extending below the base plate, the anchor comprising a tapered helix having a thread encircling a tube which tapers inwardly towards the lower end of the anchor, and a boring tip at the lower end of the anchor wherein the helix begins at the base plate and ends above the end of the boring tip a distance of no more than 50% of the combined length of the anchor and boring tip and tapers inwardly towards the lower end of the anchor at an angle of between 1 and 30 degrees relative to the vertical plane, the thread has a constant angular pitch of between 3 and 30 degrees relative to the horizontal plane and tapers from a first width proximal to the tube to a second narrower width distal to the tube, and the base plate, housing, anchor and boring tip are manufactured by extrusion.
 30. A ground anchor system for anchoring a post comprising: a base plate, a housing extending above the base plate, an anchor extending below the base plate, the anchor comprising a tapered helix having a thread encircling a tube which tapers inwardly towards the lower end of the anchor, and a boring tip at the lower end of the anchor wherein the helix begins at the base plate and ends above the end of the boring tip a distance of no more than 50% of the combined length of the anchor and boring tip and tapers inwardly towards the lower end of the anchor at an angle of between 1 and 30 degrees relative to the vertical plane, the thread has a constant angular pitch of between 3 and 30 degrees relative to the horizontal plane and tapers from a first width proximal to the tube to a second narrower width distal to the tube, and the base plate, housing, anchor and boring tip are manufactured by casting.
 31. A post anchoring system comprising: a base plate, a housing extending above the base plate, an anchor extending below the base plate, the anchor comprising a tapered helix encircling a tube which tapers inward at its lower end, a boring tip at the lower end of the anchor, and a post inserted into the housing, wherein the length of the anchor is at least 25% of the length of the overall post anchoring system.
 32. The post anchoring system of claim 31, wherein the base plate, housing, anchor, boring tip and post are structurally integrated.
 33. A method of inserting a post anchor comprising the steps of: vertically positioning the post anchor in a selected location with the tip of the post anchor in contact with the ground surface, driving the post anchor by driving means into the ground to a position in which the thread of the helix of the post anchor is in contact with the ground surface, placing a lever arm in the housing of the post anchor, simultaneously applying sufficient downward pressure and rotational torque to the lever arm to rotate the post anchor into the ground to a position in which the base plate is in contact with the ground surface, removing the lever arm, and positioning and affixing a post into the housing of the post anchor.
 34. The method of inserting a post anchor of claim 33, wherein the driving means comprises a drive shaft integrated with the lever arm. 